517
FXUS65 KBYZ 131501
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
901 AM MDT WED MAY 13 2026
KEY MESSAGES
- HOTTEST DAY YET OF 2026 TODAY, WITH TEMPS IN THE UPPER 80S TO
MID 90S (NEAR DAILY RECORD HIGHS).
- ISOLATED HIGH-BASED THUNDERSTORMS THIS AFTERNOON/EVENING COULD
PRODUCE STRONG/ERRATIC WIND GUSTS.
- PACIFIC FRONTAL PASSAGE WILL BRING STRONG WEST WINDS TONIGHT THROUGH
THURSDAY; 60+ MPH GUSTS LIKELY ALONG THE US-191 CORRIDOR FROM
BIG TIMBER TO JUDITH GAP.
- TRENDING COOLER WITH AN INCREASING CHANCE OF PRECIPITATION
(INCLUDING MOUNTAIN SNOW) THIS WEEKEND.
UPDATE
QUIET WEATHER THIS MORNING WILL GIVE WAY TO HEAT AND INCREASING
WINDS THIS AFTERNOON, PER DEEP MIXING IN A PRE-FRONTAL REGIME,
AHEAD OF A PACIFIC TROF THAT IS MOVING INLAND THRU WA/OR. ALL
EXISTING WIND HIGHLIGHTS FOR TONIGHT & THURSDAY LOOK ON TRACK, BUT
HAVE MADE A COUPLE OF ADDITIONS. MIXED SW WINDS WILL BE ORIENTED
WITH THE AXIS OF THE PARADISE VALLEY THIS AFTERNOON/EVENING, AND
FORECAST SOUNDINGS SHOW UP TO 45 KNOTS IN THE MIXED LAYER. THERE
WILL LIKELY BE MULTIPLE ROUNDS OF WEAK HIGH-BASED CONVECTION
STARTING 20-21Z, AND IT WON'T TAKE MUCH TO PUSH WIND GUSTS UP TO
60 MPH. HAVE ISSUED A HIGH WIND WARNING FOR THIS AREA FROM 1-10PM
TODAY, AFTER WHICH A COLD FRONT WILL HAVE SHIFTED WINDS TO
WESTERLY. THE OTHER LOCATION OF INTEREST IS THE CRAZY MOUNTAINS,
WHERE MOUNTAIN TOP WINDS OVER 60 KNOTS ARE EXPECTED LATER TONIGHT
INTO THURSDAY. HAVE ISSUED A HIGH WIND WARNING FOR THE CRAZY MTNS
AS WELL, FROM MIDNIGHT TONIGHT THROUGH TOMORROW, WITH PEAK WINDS
EXPECTED OVERNIGHT INTO THURSDAY MORNING.
OTHERWISE LATEST MODELS HAVE TRENDED A BIT WEAKER WITH WIND
POTENTIAL AFTER 18Z TOMORROW, SO IT APPEARS THE MAIN TIME PERIOD
OF CONCERN IS FROM THIS EVENING TO MIDDAY THURSDAY. AS FOR TODAY'S
CONVECTION, CONFIDENCE IS HIGH FOR WEAK STORMS TO PRODUCE
STRONG/ERRATIC WIND GUSTS ESPECIALLY BETWEEN 21-04Z WHEN LOW LEVEL
LAPSE RATES WILL BE STEEPEST. HEADS UP IF YOU HAVE OUTDOOR/TRAVEL
PLANS.
JKL
DISCUSSION
THROUGH NEXT TUESDAY...
UPPER RIDGING WILL CONTINUE TO BUILD OVER THE REGION, WITH THE
RIDGE AXIS SHIFTING EAST THROUGH THE DAY AS A TROUGH PUSHES INTO
THE PAC NW. AHEAD OF THE TROUGH, DOWNSLOPE FLOW AND A THERMAL
TROUGH OVER CENTRAL AREAS WILL ALLOW FOR TEMPERATURES TO CLIMB
INTO THE UPPER 80S TO LOW TO MID 90S. TODAY WILL BE THE WARMEST
DAY OF 2026 SO FAR, AND SOME RECORD HIGHS COULD BE APPROACHED.
SOUTHERLY FLOW WILL ALLOW FOR WIND GUSTS INTO THE 20S AND 30S MPH
OVER WESTERN VALLEYS AND IN THE FAR EAST, WITH A BIT LESS WIND
OVER CENTRAL AREAS. WHILE DRY CONDITIONS WILL PERSIST WITH RH DOWN
INTO THE TEENS FOR MANY AREAS, THE FAR EAST COULD SEE RH SLIGHTLY
HIGHER NEAR 20% WITH THE SOUTHERLY RETURN FLOW. THE GREEN UP IS
WELL UNDERWAY FOR THE MAJORITY OF THE LOWER ELEVATIONS, THOUGH
THE WEATHER WOULD BE PROBLEMATIC IF THERE WAS A FIRE, SO PLEASE
USE CAUTION WITH ANYTHING THAT CAUSES SPARKS.
AS THE TROUGH PUSHES EAST INTO THE NORTHERN ROCKIES,
FALLING HEIGHTS AND ENERGY LIFTING IN FROM THE SOUTHWEST WILL
BRING ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS (15-40%) TO
WESTERN AREAS DURING THE AFTERNOON, SPREADING EAST THROUGH THE
EVENING. MODEST CAPE (200-500 J/KG), STEEP LAPSE RATES AND
INVERTED-V SOUNDINGS POINT TO WIND AS THE MAIN THREAT, AND THE
CONVECTION, (T-STORM OR NOT) HAS THE POTENTIAL TO PRODUCE LOCALLY
STRONG/ERRATIC WIND GUSTS, ESPECIALLY OVER THE WESTERN HALF OF THE
AREA. A COLD FRONT ASSOCIATED WITH THE TROUGH ITSELF WILL LAG
BEHIND A FEW HOURS FROM THE ONSET OF CONVECTION, BUT THERE COULD
BE A FRONTAL/CONVECTIVE WINDS COMBO DURING THE EVENING WHICH COULD
AID IN STRONGER WINDS. THE FRONT IS EXPECTED TO DRAG WIDESPREAD 25
TO 45 MPH WINDS ACROSS THE AREA, WITH LOCALLY STRONGER GUSTS.
AS THE AFOREMENTIONED TROUGH LIFTS NORTH AND EAST INTO NORTHERN
MT/SOUTHERN CANADA, LARGE SCALE SUBSIDENCE AND STRONG
SYNOPTICALLY-FORCED WEST WINDS WILL TAKE OVER TONIGHT THROUGH
THURSDAY. MODELS CONTINUE TO DIVERGE WITH THE STRENGTH OF THE
WINDS ALOFT, WITH THE GFS PROGGING 60-70 KNOTS OF 700MB WIND OVER
NORTHWESTERN AREAS, WHILE THE EC AND NAM ARE TAMER (NEAR 50
KNOTS). REGARDLESS, CONFIDENCE IS HIGH IN STRONG WINDS IMPACTING
THE WEST AND NORTHWEST AREAS, WITH WINDS LIKELY TO REACH 60 MPH,
AND PERHAPS UP TO 70 MPH ALONG PORTIONS OF THE WESTERN FOOTHILLS.
EXPECT IMPACTS TO TRAVEL (ESP. US-191 FROM BIG TIMBER TO JUDITH
GAP) AND CANNOT RULE OUT SOME DOWNED TREES/POWER LINES IF THE
HIGHER END WINDS MATERIALIZE. TREES ARE LEAFING OUT ACROSS THE
REGION. CONFIDENCE IN WARNING LEVEL WINDS REMAINS HIGHEST FOR
AREAS FROM ROUNDUP TO BILLINGS AND WEST (40 TO 65 MPH GUSTS), WITH
GUSTS OF 30 TO 50 MPH OVER THE REMAINDER OF THE AREA. WINDS BACK
OFF LATE THURSDAY AFTERNOON INTO THURSDAY EVENING, WITH "COOL"
ZONAL FLOW AND BREEZY WINDS CONTINUING ON FRIDAY.
WHILE THURSDAY AND FRIDAY WILL BE COOLER WITH HIGHS IN THE 60S
TO MIDDLE 70S, IT WILL BE QUITE DRY WITH AFTERNOON HUMIDITY DOWN
INTO THE TEENS EACH DAY. THE STRONG WINDS ON THURSDAY MAKE THIS
THE MORE PROBLEMATIC DAY OF THE TWO, REGARDING FIRE WEATHER. WHILE
GREEN UP SHOULD HELP LIMIT A WIDESPREAD FIRE WEATHER CONCERN,
POCKETS OF ELEVATED FIRE WEATHER CONDITIONS WILL EXIST, ESPECIALLY
WHERE FUELS ARE DRIER.
LOOKING AHEAD TO THE WEEKEND AND INTO EARLY NEXT WEEK, THERE IS
THE POTENTIAL FOR A STRONGER WAVE TO MOVE INLAND FROM THE PAC NW,
EVENTUALLY LIFTING INTO THE NORTHERN ROCKIES BRINGING INCREASING
PRECIPITATION CHANCES (30-70% CHANCE) INTO MONDAY. THIS MAY BE A
DYNAMIC ENOUGH SYSTEM TO PRODUCE ACCUMULATING SNOWFALL OVER THE
MOUNTAINS, AND IF A PERIOD OF UPSLOPING MATERIALIZES WE COULD BE
LOOKING AT A DECENT PRECIP EVENT FOR OUR FOOTHILLS AND NORTH
ASPECTS. CURRENTLY THERE IS A MODERATE CHANCE AT 0.25 INCHES OF
PRECIPITATION, WITH GREATER TOTALS POSSIBLE OVER THE SOUTHERN
MOUNTAINS/FOOTHILLS. LOOK FOR HIGH TEMPS TO FALL TO THE 50S TO
LOWER 60S FOR SUNDAY/MONDAY. AN UNSETTLED WEATHER PATTERN LOOKS TO
CONTINUE NEXT WEEK, WITH POTENTIAL FOR ADDITIONAL WAVES IMPACTING
THE REGION. STP
AVIATION
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL BEGIN TO
MOVE INTO SOUTH CENTRAL MT (KLVM) AROUND 20Z TODAY, TRACKING EAST
THROUGH THE AFTERNOON. MULTIPLE ROUNDS OF THUNDERSTORMS ARE
POSSIBLE THROUGH THE EVENING, WITH GUSTY AND ERRATIC WIND GUSTS
40-50 KTS BEING THE MAIN THREAT. FOLLOWING THESE SHOWERS AND
THUNDERSTORMS (AFTER 00Z), MORE WIDESPREAD, STRONG WEST/SOUTHWEST
WINDS ARE FORECAST OVERNIGHT INTO THURSDAY (HIGHEST CONFIDENCE
OVER SOUTH CENTRAL MT). CURRENTLY, THE CHANCE OF WIND GUSTS TO 50
KTS IS 60% FOR KLVM, K6S0 AND 80% FOR K3HT. CURRENT CHANCE FOR
KBIL IS ABOUT 40%. TS/BT
PRELIMINARY POINT TEMP/POPS
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 093 055/074 048/074 043/069 042/054 037/058 038/069
2/T 20/N 00/N 00/B 55/T 53/W 12/T
LVM 090 044/068 041/068 038/063 031/047 029/054 032/065
3/T 60/N 00/N 02/W 77/T 74/W 12/T
HDN 093 053/075 045/075 041/072 041/056 036/058 035/069
2/T 20/N 00/N 00/B 45/W 54/W 11/B
MLS 091 053/074 047/072 041/073 043/058 037/058 036/067
0/N 40/N 00/N 00/B 35/W 54/W 22/W
4BQ 091 054/073 043/073 039/074 043/056 036/054 035/065
0/U 20/N 00/U 00/B 25/W 65/W 22/W
BHK 086 051/072 044/071 037/073 042/057 034/055 033/064
0/N 20/N 00/N 00/B 56/T 55/W 22/W
SHR 092 046/075 039/072 036/072 036/051 031/051 031/064
2/T 20/N 00/U 01/U 48/T 86/T 22/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...HIGH WIND WARNING IN EFFECT FROM 6 PM THIS EVENING TO 9 PM
MDT THURSDAY FOR ZONES 29-34-42-63-141-172-228-235.
HIGH WIND WARNING IN EFFECT FROM 1 PM THIS AFTERNOON TO 10 PM
MDT THIS EVENING FOR ZONE 64.
WIND ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO 9 PM MDT
THURSDAY FOR ZONES 65-66.
HIGH WIND WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 6 PM MDT
THURSDAY FOR ZONE 68.
WY...NONE.
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